An ultrasound confirms an anterior placenta covering the cervical os and an amniotic fluid index of 1.5 with a single fluid pocket measuring 1.5 x 1 cm. Over a period of 45 minutes, there are 4 episodes of fetal movement, 3 flexion/extension events, and no fetal breathing movements. The fetus is breech. Which of the following is the most likely cause of the patient's biophysical ultrasound findings?

Question

An ultrasound confirms an anterior placenta covering the cervical os and an amniotic fluid index of 1.5 with a single fluid pocket measuring 1.5 x 1 cm.  Over a period of 45 minutes, there are 4 episodes of fetal movement, 3 flexion/extension events, and no fetal breathing movements.  The fetus is breech.  Which of the following is the most likely cause of the patient's biophysical ultrasound findings?

Quizplus · Accepted Answer

11ec25c8_da50_d496_bc81_b96d83e1d283_MD0003_00 The biophysical profile (BPP) is performed to assess fetal oxygenation through ultrasound observation and the nonstress test. The components of the ultrasound assessment include measurement of amniotic fluid volume and observation of fetal tone, breathing movement, and gross body movement. Each component of the BPP is scored 0 or 2 and summed to give a score of 0 to 10. A normal BPP (8/10 or 10/10) suggests that the fetus is well-oxygenated. This patient has oligohydramnios (a single deepest pocket <2 cm or an amniotic fluid index <5) and an abnormal BPP score of 4/10. A score of 0/10 to 4/10 indicates fetal hypoxia due to placental dysfunction (placental insufficiency). Risk factors for placental insufficiency include advanced maternal age, tobacco use, hypertension, and diabetes. The patient requires prompt delivery due to the high likelihood of fetal demise. < (Choice A) Malpresentation is associated with fetal growth restriction and may be a result of chronic fetal hypoxia, but it does not cause oligohydramnios or an abnormal BPP. (Choice B) Decreased fetal movement is often caused by maternal hypoglycemia. However, maternal hypoglycemia is not associated with a low amniotic fluid volume. (Choice D) Patients with an anterior placenta more frequently report a decrease in fetal movement as this placental position may make perception of movement more difficult. However, there is no association between placental location and an abnormal BPP. (Choice E) Although a BPP performed on an extremely premature infant is difficult to interpret due to the immaturity of the preterm fetal nervous system, a 35-week fetus would be expected to have a well-developed central nervous system and a normal BPP. Educational objective: An abnormal biophysical profile score (eg, 4/10) is consistent with fetal hypoxia. Prompt delivery is indicated due to the high probability of fetal demise. References: ACOG practice bulletin no. 145: antepartum fetal surveillance. (http://www.ncbi.nlm.nih.gov/pubmed/24945455) Fetal biophysical profile. (http://www.ncbi.nlm.nih.gov/pubmed/10587955) Antenatal fetal surveillance. (http://www.ncbi.nlm.nih.gov/pubmed/15017340)

An Ultrasound Confirms an Anterior Placenta Covering the Cervical Os